The Victorian Government is failing its obligations as a parent to wards of the state with its treatment of young people leaving residential care, the state's Children's Commissioner says.

Commissioner Bernie Geary has backed peak child protection and homelessness agencies in calling for a rental assistance scheme to help all young people when they were forced to leave care at the age of 18.

"It's not just about four walls and a roof, it has to do with ongoing support - children need the assistant of adults when they need them," Commissioner Geary said.

Police hunting the killer of Melbourne sex worker Tracy Connelly say that a year on from her stabbing death they are still waiting on Interpol to provide any relevant DNA data.

Connelly, 40, was found dead in her van in St Kilda's red-light district on Greeves Street on July 21, 2013.

Earlier this year it was revealed that Victoria Police reached out to the international police agency to review the DNA traces found in Connelly's van against the agency's 192 databases across the world.